Process for cleaning ovens and like devices

ABSTRACT

A process for cleaning food spills from ovens and the like devices which comprises the steps of applying a composition which consists essentially of from 1 to 35 percent by weight of a polydimethylsiloxane having a viscosity of at least 3000 cs. at 25* C., from 0.5 to 5.5 percent by weight of a siloxane resin composed of SiO4/2 units and (CH3)3SiO1/2 units in the ratio of 1:0.6-1.2, from 0.1 to 9 percent by weight of a metal oxide, and the balance solvent, to the clean and essentially dry surfaces of the oven or like device, and then, after the oven or device has been employed one or more times for heating food, cleaning the food spills therefrom, said cleaning being facilitated by said composition.

United States Patent [72] Inventors [54] PROCESS FOR CLEANING OVENS ANDLIKE DEVICES 12 Claims, No Drawings 52 us. c1 134/29, 106/2, 106/287s13,117/13s.1,134/2,134/4,

51 1 1111. c1 13081117/02, "13086 31/08, C09k 3/00 150 1 Field 61 Search134/2, 4, 6, 29, 40, 42,22 R, 39; 106/2, 287 s13;117/13s.1

[5 6] References Cited UNITED STATES PATENTS 2,473,887 6/1949 Jenningset a1. 106/2 X 2,743,192 4/1956 White .....l06/287 SB UX 3,l83,l l05/1965 Aler e t a1. l06/287 SB Primary Examiner-Morris O. Wolk AssistantExaminer-Barry S. Richman Attorneys-Robert F. Fleming, .lr., Laurence R.Hobey, Harry D. Dingman, Howard W. Hermann and Jack E. MoermondABSTRACT: A process for cleaning food spills from ovens and the likedevices which comprises the steps of applying a composition whichconsists essentially of from 1 to 35 percent by weight of apolydimethylsiloxane having a viscosity of at least 3000 cs. at 25C.,from 0.5 to 5.5 percent by weight ofa siloxane resin composed of S10units and (CH ),,SiO,, units in the ratio of 1:0.6-1 .2, from 0.1 to 9percent by weight of a metal oxide, and the balance solvent, to theclean and essentially dry surfaces of the oven or like device, and then,after the oven or device has been employed one or more times for heatingfood, cleaning the food spills therefrom, said cleaning beingfacilitated by said composition.

PROCESS FOR CLEANING OVENS AND LIKE DEVICES The care and cleaning ofovens is a difficult and usually I thankless task, particularly for thehousewife. Attempts to make this task easier can be classified intothree or four basic categories. In one category there is the pyrolyticovens which are self-cleaning" in nature. Such ovens are cleaned byheating the interior of the oven to such a high temperature that anyfood spills are oxidized or burned away. Aside from any inadequacies ofthe cleaning job that such ovens do, they have the obvious disadvantagesattendant to the use of high temperatures, namely, providing ampleinsulation to prevent damage from heat or a fire and means forventilating and cooling the surrounding areas. The problems inherent inthe pyrolytic ovens has led to the development of the second categorywhich is the self-cleaning catalytic ovens. Catalytic ovens are much thesame as pyrolytic ovens, and perhaps should be categorized with them,but by one means or another they provide for the presence of a catalyston the interior surfaces whereby the pyrolytic oxidation and/or burningaway of food spills is supposedly achieved at lower temperatures.However, these catalytic ovens do not entirely overcome the aboveproblems of the pyrolytic ovens and are less than thorough in cleaningaway food spills.

I In the third category there are the chemical compositions which whenapplied to the soiled oven surfaces are supposed to remove the foodspills. Basically these compositions usually contain strong or harshalkaline detergents and/or solvents. The problem with this approach hasbeen that thecompositions will remove some types of food spills but notthe full range of food spills encountered by theaverage housewife.Moreover, when one attempts to formulate a composition which wouldprovide the desired cleaning action in a reasonable amount of time, ithas been found that the compositions are too dangerous for safe use inthe home.

The processes of cleaning ovens involving application of a substance tothe surface of an oven to facilitate the removal of food spills withmild detergents or cleaning agents such as soap constitutes the fourthcategory. It is into this category which the present invention falls.Early efforts in this area involved the application of silicone resinsto the oven surfaces which were then'curecl to form 'a film thereon.However, such films became broken during use exposing the oven surfaceand did not facilitate removal of all types of food spills.Subsequently, the use of silicone fluids was tried for the protection ofoven surfaces and while reapplication of this material to any area ofthe oven-where necessary was now practical, these compositions stillfailed to facilitate removal of all of the basic types of food spillsnormally encountered.

It is an object of this invention to provide a process for cleaningovens and the like devices whereby the removal of food spills therefromis facilitated.

Another object of this invention is to provide a process for cleaningindustrial ovens and similar devices which are employed for baking,cooking and heating foods and from which food spills must beperiodically removed whereby the cleaning of the food spills therefromis facilitated.

Still another object of this invention is to provide a composition foruse in the above process which aids in the cleaning process.

Other objects and advantages of this invention will be apparent to thoseskilled in the art from the following detailed description.

This invention relates to a process for cleaning food spills from ovensand the like devices which comprises the steps of applying a compositionwhich consists essentially of from I to 35 percent by weight of apolydimethylsiloxane having a viscosity of at least 3000 cs. at 25' C.,from 0.5 to 5.5 percent by weight of a siloxane resin composed of SiOnsunits and (CH ,SiO units in the ratio of l:0.6-l.2, from 0.1 to 9 percent by weight of a metal oxide, and the balance solvent, to the cleanand essentially dry surfaces of the oven or like device, and then, afterthe oven or device has been employed one or more times for heating food,cleaning the food spills In the process, the composition can be appliedto the desired surfaces, for example those of an oven, by any of theconventional means for applying materials. For example, the compositioncan be brushed, dabbed, wiped or sprayed onto the surface. Probably themost convenient means of applying the composition and obtaining arelatively uniform application is via an aerosol. Any of the well-knownpropellants used in aerosols, such as isobutane, nitrogen, nitrous oxideand the halocarbons, can be employed. The halocarbon propellants arepreferred. When the composition is applied, the surface should be bothclean and essentially dry. The exact amount of the composition appliedto the surface to be treated is not critical but should be enough toform a substantially complete coating on the surface. MOre than this canbe applied but is not known to provide any additional benefit. Afterapplication it is best to allow a waiting period of 20 to 30 minutesbefore useoftheoven.

Once the composition employed in the'process is'applied to the surfaceit does not cure but as a general rule forms a tacky or wet coatingthereon. After use of the oven or other device one or more times, withattendant food spillage, the spills are removed. Cleaning or spillremoval can-be by any of the usual means employing a mild detergent andin most instances using only warm soapy water and a dish cloth, papertowel or sponge. Tlnthe event of a stubborn spill, this can be removedwith a plastic scrubber and minimal effort. One of the advantages of theprocess of this invention is that it is not necessary to clean the ovenafter each use or spill but it can be cleaned weekly, monthly or evenless often (depending on usage) without worrying about the food spillsbaking onto the surface. Moreover, it is not necessary to heat the ovento high temperatures, cleaning being accomplished in a cold (i.e., roomtemperature) oven. However, once one spot cleans or thoroughly cleansthe surfaces it is necessary to apply more of the composition to insureproper performance.

The composition employed in the process of this invention forfacilitating the cleaning of ovens and the like devices consistsessentially of from I to 35 percent by weight of a polydimethylsiloxanehaving a viscosity of at least 3,000 cs. at 25 C., from 0.5 to 5.5percent by weight of a siloxane resin composed of SiO.,, units and(CH,),SiO,,, units in the ratio of l:0.6-1.2, from 0.] to 9 percent byweight of a metal oxide, and the balance solvent. I

In the basic composition the first essential component is apolydimethylsiloxane having a viscosity of at least 3,000 cs. at 25 C.So far as is known at this time there is no critical upper limit as tothe viscosity of this siloxane and even polydimethylsiloxane gums (a gumbeing a material having a viscosity greater than 1,000,000 cs. at 25 C.)can be employed. For best results, however, it is preferred that thepolydimethylsiloxane be a fluid having a viscosity in the range of about12,500 to 40,000 cs. at 25 C. It should be noted at this point that whenthe term "viscosity" is employed herein, it can refer to the property ofa fluid composed of a single siloxane or of a fluid composed of two ormore siloxanes which have been blended together to obtain the desiredviscosity. It is not necessary that all of the siloxanes in a blend havea viscosity of at least 3000 cs., i.e. some siloxanes can haveviscosities of less than 3000 cs., so long as the ultimate viscosity ofthe fluid used is at least 3000 cs. So far as is known at this time anypolydimethylsiloxane can be employed in the composition of thisinvention regardless of the method by which it is prepared. Many suchsiloxanes are commercially available and thus would be the siloxanesnormally used. While the polydimethylsiloxane can constitute from 1 to35 percent by weight of the composition, for best results the amountemployed should be within the range of 10 to 15 percent.

The second essential component in the composition is a siloxane resincomposed of SiO.,-, units and (CH,),SiO,, units. The ratio of SiO.,,units to (CH,) ,SiOl/Z units in this resin must be within the range ofl:0.6-l.2. This resin is commercially available and can be prepared byvarious processes therefrom-said cleaning being facilitated by saidcomposition. 5 known to those skilled in the art. One such process isdescribed in U.S. Pat. No. 2,676,182 the disclosure of which isincorporated herein by reference. As prepared, this resin normallycontains about 2 to 3 percent by weight of siliconbonded hydroxylgroups, i.e.z aSil-l groups. It was found quite unexpectedly that whenthe content of the silicon-bonded hydroxyl groups on the siloxane resinwas reduced to less than 1.0 percent by weight, not only was thecompositions ability to facilitate the removal of all types of foodspills enhanced, but also the period of time over which removal of suchspills is facilitated was extended. The content of the silicon-bondedhydroxyl groups in the resin can be reduced in several ways. Thesimplest way to accomplish this result is to mix a trimganosilylamine orbis(triorganosilyl)amine with the resin as prepared. This results in thereplacement of the hydroxyl groups with triorganosilyl groups. Thisreaction is illustrated by the equations below wherein R represents anyhydrocarbon radical. Specific examples of suitable amines are dimethylvinylsilylamine and bis(trimethylsilyl)amine. v (l R,siNH, +HOSiR,SiOSij+NH,

The amount of siloxane resin in the composition must be within the rangeof 0.5 to 5.5 percent by weight and is preferably within the range of0.75 to 2.5 percent by weight. It should be noted that this resin willusually be incorporated in the composition of this invention in the formof a solvent (for example xylene) solution for ease of handling but thatthe ranges of resin specified above and elsewhere refers to the resinsolids and not the amount of the solution added.

The third essential component in the basic composition described aboveis from 0.1 to 9 percent by weight of a metal oxide. It is notcompletely understood how the metal oxide functions in the compositionbut it is known that its presence, in the above stated quantity, extendsthe time during which the composition facilitates the cleaning of ovensand the like devices. This component also accelerates the processwhereby fat and grease spills tend to shrink in size, crack and peelfrom the surface when the composition is used. For example, the oxidesof vanadium, chromium, molybdenum, manganese, iron cobalt, nickel,copper, aluminum, tin, titanium, silicon, bismuth and cerium can beemployed herein.

The fourth essential component, which makes up the balance of thecomposition, is the solvent. Any solvent can be employed since thefunction of this component is merely that of a vehicle or means forapplying the other components to the desired surface. For reasons ofsafety, particularly when a household product is involved, it ispreferred that the solvent be one which has a high flash point or whichis nonfiammable, and presents little hazard to physical health. By wayof illustration one can employ any of the well known organic (i.e.,nonsilicone) solvents such as toluene, xylene, petroleum naphtha,acetone, VM & P naphtha, stoddard solvent, mineral spirits, benzenemethylisobutyl ketone, butyl alcohol, tetrachloroethane,monochlorobenzene, ethyl acetate, 1, l, l -trichloroethane and hexane.At this time it is preferred that the solvent be a hydrocarbon or ahalogenated hydrocarbon solvent. The term solvent" as used herein isintended to include mixtures of solvents as well as a single solvent. Asstated above, the solvent makes up the balance of the composition whichis from 50.5 to 98.4 percent by weight of the composition.

The compositions employed in the instant process are prepared by simplymixing the ingredients together in the appropriate proportions. So faras is known at this time. there is no critical order in which theingredients are mixed. With respect to the metal oxide, it has beenfound that this can best be added by mixing it with thepolydimethylsiloxane prior to mixing with the other ingredients. Afterthe composition has been prepared, if it has been standing for sometime, it should be shaken well to make sure that the metal oxide isthoroughly dispersed throughout the composition prior to the applicationof the composition in accordance with the process.

Now in order that those skilled in the art may better understand how thepresent invention can be practiced, the following examples are given byway of illustration and not by way of limitation. All parts and percentsreferred to herein are on a weight basis, and all viscosities measuredat 25C., unless otherwise specified.

In the examples the various compositions prepared were evaluatedaccording to the following procedure.

A clean, dry, gray, 4 inch X 6 inch porcelain panel was placedvertically in an exhaust hood. The composition to be tested was shakenvigorously and poured into a .let-Pak Spray Unit. The spray unit wasshaken and then the composition sprayed onto the panel. The sprayoperation consisted of slow, sweeping, horizontal motions and movingfrom top to bottom of the panel. A substantially complete coating of thecomposition was applied to the panel by this technique.

Next, the panels were placed in an electric oven and heated for about1/2 hour at 350 F. To these hot panels there was applied a glob of acommercial cherry pie filling and a glob of a commercial cheese paste.Then a warm mixture of hamburger grease and chicken grease wassplattered onto the panels using a spatula. These materials are believedbelieved to represent the most difficult types of food spills to remove.

Both shelves of the oven were used to hold the panels, with the shelvesbeing set at the lowest levels. No more than ten panels were placed on ashelf at one time.

Tl-le panels containing the food spills were subjected to a 20 hourvariable temperature heating cycle which involved heating for two hoursat each of the following temperatures in the order indicated: 300 F.,375 F., 325 F., 400 F., 350 F., 300 F., 375 F., 325' F., 400 F., and 350F., After the first 10 hours of heating, the shelves were rotated so asto allow equal exposure to the lower heating coil. Twenty hours ofheating in this cycle represents approximately 25:5 calendar days ofnormal oven usage.

Upon completion of .the heating cycle the panels are removed from theoven, allowed tocool to room temperature and then subjectively evaluatedfor ease of cleaning according to the following rating systems.

Cherry pie filling and cheese spills Excellent (E)-spill slides from thesurface with no crust remaining.

Very Good (VG)-spill slides from the surface with only a few scatteredspots of crust remaining.

Good (G)most of the of slides from the surface but some efiort neededand with a slight amount of crust remaining.

Fair (F )only one-half or less of the spill removes from the surfacewith considerable effort needed.

Poor (P)-very little or none of the spill removes from the surfacedespite considerable effort.

Grease spills The term wiping action" as used herein means the use of amoist, soapy, paper towel, cloth, sponge or plastic scrubber to affect acleaning.

Excellent (E)-splatters break easily and slide from the surface with aslight wiping action.

Very Good (VG-splatters break easily and slide from the surface aftersomewhat more wiping action than an excellent rating.

Good (G)about one-half of the splatters break from the surface afterabout the same wiping action required for a very good rating.

Fair (F )only a slight amount of the splatters removed afterconsiderable wiping action.

Poor (P)splatters are firmly attached to the surface despiteconsiderable wiping action.

The degree of shrinkage of the grease spills was evaluated according tothe following scale:

Very Good (VG) Good (6) l Slight (S) Very Slight (VS) Very Very Slight(VVS) None (N) The feel of the composition of the panel after theheating cycle and cooling was rated according to the following system.

EXAMPLE 3 A series of compositions was prepared whichconsistedessentially of about. 4 percent of apolydimethy lsiloxane havinga paredby blending,.3'.33 perylsiloxane and. 0.61 percent of ne varying amountsof the ab'out 0.5 percent of manganese ,l,l-trichloroethane. These com-Ease of spill removal Percent Cherry Grease Compoposisiloxane eshrinksltlon resin filling Cheese Grease age feel 5 viscosity ofabout.30,000 cs..(pre

centof a. 60,000 cs. polydimeth a 1000. cs. polydimethylsiloxa siloxaneresin of example i dioxide and the. balance l ylsiloxanes Com h varyingviscosities, about 1 percent of a siloxane resin tion composed of Slounits and (CH SiO l:0.61.2 and containing about 0.66 hydroxyl groups,about 0.5 percent Dry (D) Slightly Wet (SW) Very Slightly Wet (VSW)Tacky (T) Very Tacky (VT) Slightly Tacky (ST) Very Slightly Tacky (VST)EXAMPLE 1 A series of compositions was prepared which consistedessentially of about 4 percent of various polydimeth wit m units in theratio of PPEEEEGPPPPP G GG EEEEEEVGVVEE 2 dd 6 en 8 m m. u ow .0 r o n m8 m .m .m .m d H .m S N t. mn 8 n m n .1 mm m e or IV... 0. m

the balance l,l,l-trichloroethane as the solvent. The siloxane resin wasadded as a 6 8 percent solids solution: in xylene. The compositions wereprepared b together.

The above-prepared compositions were evaluated according tothe'procedure described above and the results a pecific nature of' the 0stiq thjyhstelfls' Ease of spill removal Cherry Viscosity ePolydlmethylslloxane (cs) filling Cheese forth in the table below. The spolydimethylsiloxanes employed als Composition wwwTTTwwwwwwwTTTnn F G GPPGEVEPPPPPVFEEEGF GPEEEEPPPPFFEEEFEE G G VPEEEEPPGPGFEEEFEVmmmmmmmmmwmmmmwmmm um mwmmmm EXAMPLE 4 A series of compositions wasprepared as in example 3 except that the amount of siloxane resinemployed was about I Composltlon feel purposes of comparison. 0% soutlon in 1,1,1-trlchloroethane.

EXAMPLE 2 positions were evaluated as in example i and the test resultsI l are set forth in the table below as well as the amount of resin in p6 the composition. t 2.4 peri positions t forth in Ease of spill removalCherry Grease Viscosity pie shrink- Polydlmethylsiloxane (cs.) fillingCheese Grease age I Included for 1 Added as 1 9 91..

A series of compositions was prepared as in exam cept that the siloxaneresin employed contained abou cent of silicon-bonded hydroxyl groups.These com were evaluated as in example i and the results are se thetable below.

Composition FFPPPPPPPP GG G EEEEEEPPFVVEEEEVEE EEEEEEEEEEEEEEGEEEmmmmmmmmmmmm m no uwmmmm I Included for purposes of comparison. I Addedns 10% so utlon in 1,1,l-trlchloroethane.

ABcDsRoHIJKLMMoRWR percent and the amount of the manganese dioxidevaried. These compositions were evaluated as in example 1 and the testresults are set forth in the table below as well as the amount ofmanganese dioxide in the composition.

Ease of spill removal A series of compositions was prepared as inexample 3 except that the amount of siloxane resin employed was about 1percent and that various metal oxides were employed. These compositionswere evaluated as in example I and the test results are set forth in thetable below as well as the metal oxides employed.

Grease Composishrinkage tron feel VG T G-VG T VS-S T VS-S T EXAMPLE 6 Aseries of compositions was prepared as in example 3 except that theamount of siloxane resin employed was about 1 percent and the amount ofthe polydimethylsiloxane varied. These compositions were evaluated as inexample 1 and the test results are set forth in the table below as wellas the amount of the polydimethylsiloxane in the composition.

' Ease of spill removal Percent polydi- Cherry Grease Compo- Compos1-methylpie shrinksition on siloxane filling Cheese Grease age feel A 0.10P-F P-F P N D B 0.20 P P P N D C 0.30 E E P-F N D D 0.50 E E VG-E S VSTE 0.75 E E VG-E S VST F. 1.0 E E E S-G ST G. 2.0 E E E G-VG T IL 4.0 E EE G T 1-. 8.0 E G VG VS-S T J 12.0 E E E S '1 l 7 I included forpurposesof comparison.

EXAMPLE 7 A composition was prepared which consisted essentially ofabout 4 percent of a polydimethylsiloxane having a viscosity of about30,000 cs. (prepared by blending 3.33 percent of a 60,000 cs.polydimethylsiloxane and 0.67 percent of a i000 cs.polydimethylsiloxane), about I percent of a siloxane resin composed ofSiO,,, units and (CH,),SiO,,, units in the ratio of l:0.6l .2 andcontaining about 0.66 percent of silicon-bonded hydroxyl groups, about0.5 percent of manganese dioxide, about 0.5 percent xylene (solvent inwhich the siloxane resin was added), about 29 percent 1,],l-trichloroethane, about 40 percent of trichloromonofluoromethane andabout 25 percent of dichlorodifiuoromethane, the latter two ingredientsfunctioning as solvents as well as propellants. This composition wasplaced in an aerosol container. When this composition was applied to thewalls of a clean, dry oven, and then the oven used for heating foods,the food spills could be easily removed by cleaning the oven with warmsoapy water and paper towels.

T txth hissl ims is l. A process for cleaning food spills from ovens andthe like devices which comprises the steps of applying a coatingcomposition which consists essentially of from I to 35 percent by weightof a polydimethylsiloxane having a viscosity of at least- 3000 cs. at 25C., from 0.5 to 5.5 percent by weight ofa siloxane resin composed ofSiO,,, units and (CHQ SiO units in the ratio of l:0.6-L2 from 0.1 to 9percent by weight of a metal oxide, and the balance solvent, to theclean and essentially dry surfaces of the oven or like device, and then,after the oven or device has been employed one or more times for heatingfood, cleaning the food spills therefrom, said cleaning beingfacilitatedbysaid composition.

2. A process as defined in claim 1 wherein the metal oxide is selectedfrom the group consisting of the oxides of vanadium, chromium,molybdenum, manganese, iron, cobalt, nickel, copper, aluminum, tin,titanium, silicon, bismuth, and cerium. 35A process as defined in claim1 wherein in the composition there is from 10 to 15 percent of apolydimethylsiloxane having a viscosity in the range of 12,500 to 40,000cs., and 091112-1292 2.; per n of the i o n resin,

4. A process as defined in claim 3 wherein the composition is appliedvia an aerosol and the cleaning step is performed by contacting thesoiled coating with warm soapy water.

5. A process as defined in claim 3 wherein the metal oxide is selectedfrom the group consisting of the oxides of vanadium, chromium,molybdenum, manganese, iron, cobalt, nickel, copper, aluminum, tin,titanium, silicon, bismuth and cerium.

6. A process as defined in claims wherein the metal oxide is manganesedioxide.

7. A process as defined in claim 5 wherein the metal oxide is aluminumoxide. V: p

8. A process as defined inclaim 3 wherein in the composition thesiloxane resin contains less than 1.0 percent by weight ofsilicon-bonded hydroxyl groups.

9. A process as defined in claim 8 wherein the composition is appliedvia an aerosol and the cleaning step is performed by contacting thesoiled coating with warm soapy water.

10. A process as defined in claim 8 wherein the metal oxide is selectedfrom the group consisting of the oxides of vanadium, chromium,molybdenum, manganese, iron, cobalt, nickel, copper, aluminum, tin,titanium, silicon, bismuth and cerium.

l 1. A process as defined in claim 10 wherein the metal oxide ismanganese dioxide.

12. A process as defined in claim 10 wherein the metal oxide is aluminumoxide.

U.S. PATENT OFFICE UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent NO. 5,615,826 Dated: 10/26/71 Alfred P. Brill and Leroy A KeiserIt is certified that errors appear in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

No Assignee is given for this patent, please add Assignee Dow CorningCorporation Midland, Michigan" This assignment was recorded in theUnited States Patent Office on March 31, 1971 on Reel 2705, Frames 6 65.

Signed and sealed this 2nd day of May 1972.

(SEAL) lttest:

iDWARD M.FLETCHER, JR. ROBERT GOTI'SCHALK Lttesting Officer Commissionerof Patents

2. A process as defined in claim 1 wherein the metal oxide is selectedfrom the group consisting of the oxides of vanadium, chromium,molybdenum, manganese, iron, cobalt, nickel, copper, aluminum, tin,titanium, silicon, bismuth, and cerium.
 3. A process as defined in claim1 wherein in the composition there is from 10 to 15 percent of apolydimethylsiloxane having a viscosity in the range of 12,500 to 40,000cs., and from 0.75 to 2.5 percent of the siloxane resin.
 4. A process asdefined in claim 3 wherein the composition is applied via an aerosol andthe cleaning step is performed by contacting the soiled coating withwarm soapy water.
 5. A process as defined in claim 3 wherein the metaloxide is selected from the group consisting of the oxides of vanadium,chromium, molybdenum, manganese, iron, cobalt, nickel, copper, aluminum,tin, titanium, silicon, bismuth and cerium.
 6. A process as defined inclaim 5 wherein the metal oxide is manganese dioxide.
 7. A process asdefined in claim 5 wherein the metal oxide is aluminum oxide.
 8. Aprocess as defined in claim 3 wherein in the composition the siloxaneresin contains less than 1.0 percent by weight of silicon-bondedhydroxyl groups.
 9. A process as defined in claim 8 wherein thecomposition is applied via an aerosol and the cleaning step is performedby contacting the soiled coating with warm soapy water.
 10. A process asdefined in claim 8 wherein the metal oxide is selected from the groupconsisting of the oxides of vanadium, chromium, molybdenum, manganese,iron, cobalt, nickel, copper, aluminum, tin, titanium, silicon, bismuthand cerium.
 11. A process as defined in claim 10 wherein the metal oxideis manganese dioxide.
 12. A process as defined in claim 10 wherein themetal oxide is aluminum oxide.